EXPRESSION OF SECRETORY MUCIN GENES BY HUMAN CONJUNCTIVAL EPITHELIA

Purpose. To determine whether human conjunctival epithelium expresses any of the human mucin genes designated MUGS through MUC7. Method. Nor thern blot analysis was performed using total RNA isolated from surgic ally removed conjunctival tissues. Complementary DNA or oligonucleotid es to the tandem repeat region of each mucin gene were labeled and hyb ridized to conjunctival RNA. In situ hybridization also was performed to determine the distribution of mucin mRNA, Results. Only MUC4 and MU C5 probes hybridized to conjunctival RNA by Northern blot analysis. Bo th probes bound in a polydispersed pattern, which is characteristic of mucin genes. Using in sim hybridization, MUC4 mRNA was detected in th e cells of the stratified conjunctival epithelium, whereas MUC5 mRNA e xpression was limited to goblet cells. MUC4 or MUGS probes did not hyb ridize to sections of corneal epithelium. Conclusions, The mucins MUC4 and MUC5 are expressed by the human conjunctiva. These mucins may pla y an important role in forming the tear-film layer at the air and ocul ar surface epithelium interface.